Poverty increases children's exposure to stress, which heightens risk for developing patterns of exaggerated autonomic reactivity. High-reactivity is a risk factor for developing anxiety disorders. The proposed study evaluates whether providing social support during stress to preschool-age children living in poverty reduces autonomic responses, and whether this effect depends on baseline reactivity patterns. Biological Sensitivity to Context (BSC) theory proposes that highly reactive children may be more sensitive than less reactive children to all environmental influences, including social support. Traditional physiological reactivity (TPR) theories contend that highly reactive children are more vulnerable to the impact of stress, but are less receptive to the potential benefits of their social environments. In the proposed study, baseline autonomic reactivity patterns will be measured. Children will then be randomly assigned to a high-support or neutral condition, and the effect of social support on autonomic responses will be assessed. Results will elucidate dispositional (i.e., baseline reactivity patterns) and contextual (i.e., social support levels) influences on children's autonomic stress responses, evaluating BSC and TPR theories. Reactivity patterns are still quite susceptible to change at this age; therefore understanding whether social support ameliorates reactivity will further efforts to avert stable patterns of high-reactivity in children living in poverty, reducing risk for anxiety disorders. Recent epidemiological research indicates that anxiety disorders are more common among preschool age children than all other mental health disorders, with nearly 10 percent of children aged two to five meeting diagnostic criteria for an anxiety disorder. Furthermore, children with anxiety disorders, relative to non-anxious children, have a broader range of psychosocial difficulties, including impairment in social relations and behavior, depression, attention, academic performance, and self-esteem. The pervasiveness of anxiety disorders among young children, and the negative impact they have on psychosocial functioning, strongly support the public health importance of investigating early risk factors for anxiety, such as high physiological reactivity to stress, and studying methods of early intervention to ameliorate this risk. [unreadable] [unreadable] [unreadable]